Don't worry about the VTA. It changes anyway with different cartridges.
You want to remove the rubber mat and adhere the cork mat to the plater with a spray contact cement. The mat should have a depression for the record label. Lacquer thinner can always remove the contact cement.
You want to remove the rubber mat and adhere the cork mat to the plater with a spray contact cement. The mat should have a depression for the record label. Lacquer thinner can always remove the contact cement.